It's a good concept and everything; I just don't see more then a few people paying for the premium membership.
You should add one thing to the premium: You can't be banned for little things like trolling. If you pay you've earned the right to troll.
Also instead of just monthly for $7.99 you could give a yearly option for like $69.99 or something and give people a good deal if they make the long term commitment.
Last thing the data would have to be on time. Since its free right now I never complain about the numbers being later then usual, but if I'm paying $8/month to see them I'd like them the same time every week.
Edit: If the things I mentioned (yearly payment option, way less bans & numbers on time every week) then there's a much higher chance I'd pay.
Edit 2: Also to thank current members for supporting the site; you could give a much discounted price (like $40 for the first year) to current members with either over 500 or over 1000 posts; something like that to thank them for our loyalty! Because basically just by coming to the site we're supporting it by increasing the value of ad space on the site.
Edit 3: You mentioned MAYBE no ads for people who pay the $8/month. How about you forget about no ads (keep the ads, because they're only a minor annoyance) and make it $5/month which sounds more reasonable.
